A conventional vehicle head-up display device disclosed in, for example, PTL 1 has been known. The vehicle head-up display device in PTL 1 includes a liquid crystal display panel and a light emitting element that illuminates the liquid crystal display panel. The vehicle head-up display device projects a display light including a linearly polarized light onto a windshield to display the virtual image.
The vehicle head-up display device of PTL 1 rotates a polarization axis of the display light by a retardation plate, which is separately prepared, to improve the visibility of the virtual image as viewed over sunglasses.